RFC2833 DTMF uses an out-of-band approach. The idea here is that special Real-Time Transport Protocol (RTP) even messages are sent instead of the raw tones. For example, a message is sent indicating a "DTMF digit 7" versus sending the two frequencies that make up a DTMF 7. This approach is more reliable.
Dig Deeper on VoIP Migration and Implementation
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.